Discovery and optimization of 2-(trifluoromethyl)benzimidazole derivatives as novel ferroptosis inducers in vitro and in vivo.

Ferroptosis is implicated in diverse human diseases. Ferroptosis inducers hold great potential for cancer therapy. The existing ferroptosis inducers, however, lack structural diversity, and only a few of them are suitable for in vivo applications. Herein, by phenotypic screenings, we discovered a new ferroptosis inducer FA-S, a 2-(trifluoromethyl)benzimidazole derivative, from which a series of its analogs were designed and synthesized to improve the activity. This produced the most potent compound FA16 with single-digit micromolar activity of ferroptosis induction and satisfactory metabolic stability. Further studies demonstrated that FA16 induced ferroptosis by inhibiting cystine/glutamate antiporter (system X). It is noteworthy that analogue FA16 has more favorable metabolic stability than the classic system X inhibitor erastin, which is not suitable for in vivo studies. FA16 significantly inhibited tumor growth in the HepG2 xenograft model by inducing ferroptosis. This work provides new ferroptosis inducers with a novel scaffold, but also a promising lead for hepatocellular carcinoma treatment. Our work reveals a suitable in vivo ferroptosis-inducing tool to explore the mechanisms underlying ferroptosis and the relevance of ferroptosis to pathogenesis of human diseases.